JP2016176507A - Ball screw device and nut member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ball screw device capable of preventing the slipping-off of a rolling body without using a temporary shaft, and a nut member.SOLUTION: A ball screw device includes: a screw shaft 2 which has a spiral ball rolling groove 21 on an outer peripheral surface 2a; a nut member 3 which has a spiral ball load rolling groove 31 opposite to the ball rolling groove 21 on an inner peripheral surface 3b; and a plurality of balls 4 interposed between the ball rolling groove 21 and the ball load rolling groove 31. The nut member 3 has a ball holder 50 having a spiral linear portion 51 opposing to the ball load rolling groove 31 and holding the balls 4 in the ball load rolling groove 31. The screw shaft 2 has a spiral relief groove 24 formed in the ball rolling groove 21, and the linear portion 51 of the ball holder 50 is stored in the relief groove 24.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a ball screw device and a nut member.

  The ball screw device includes a screw shaft having a spiral rolling element rolling groove on the outer peripheral surface, a nut member having a spiral rolling element load rolling groove facing the rolling element rolling groove on the inner peripheral surface, and A plurality of rolling elements interposed between the rolling element rolling grooves and the rolling element load rolling grooves. When either one of the screw shaft and the nut member is rotated, the other linearly moves in the axial direction. As such a ball screw device, for example, a ball screw described in Patent Document 1 below is known.

Japanese Patent No. 5644668

  By the way, if a nut member is pulled out from a screw axis, a rolling element will fall from a nut member. For this reason, conventionally, the temporary shaft is connected to the screw shaft, and the rolling element is prevented from falling off by connecting the nut member from the screw shaft to the temporary shaft. However, if a temporary shaft is used, the temporary shaft is necessary every time the nut member is inserted and removed, which is inconvenient. Further, in the manufacturing process, since the rolling element is incorporated so that the temporary shaft does not contact the inner peripheral surface of the nut member, the assembling work of the rolling element is complicated. In addition, even if the temporary shaft is used, if the temporary shaft is tilted with respect to the central axis of the nut member, the rolling elements will fall off the nut member.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a ball screw device and a nut member that can prevent the rolling element from falling off without using a temporary shaft.

  In order to solve the above-described problems, the present invention provides a screw shaft having a spiral rolling element rolling groove on the outer peripheral surface, and a spiral rolling element load rolling facing the rolling element rolling groove on the inner peripheral surface. A ball screw device comprising: a nut member having a moving groove; and a plurality of rolling elements interposed between the rolling element rolling groove and the rolling element load rolling groove, wherein the nut member is the rolling member. A rolling element retainer having a spiral linear portion that holds the rolling element in the rolling element load rolling groove facing the rolling element load rolling groove, and the screw shaft includes the rolling element rolling groove A configuration is adopted in which a spiral relief groove formed in the clearance groove is formed, and the linear portion of the rolling element retainer is accommodated in the relief groove.

  Further, the present invention is a nut member having a spiral rolling element load rolling groove on an inner peripheral surface, wherein the rolling element load rolling is opposed to the plurality of rolling elements and the rolling element load rolling groove. A configuration is adopted in which a rolling element holder having a spiral linear portion that holds the rolling element in the groove is employed.

  ADVANTAGE OF THE INVENTION According to this invention, the ball screw apparatus and nut member which can prevent dropping of a rolling element without using a temporary shaft are obtained.

It is a front view of a ball screw device in an embodiment of the present invention. It is arrow AA sectional drawing in FIG. It is a principal part enlarged view in FIG. It is a disassembled perspective view of the nut member in embodiment of this invention. It is a left view of the nut member which removed the retainer cap in the embodiment of the present invention. It is a right view of the 1st retainer cap in the embodiment of the present invention. It is arrow BB sectional drawing in FIG. It is a left view of the 2nd retainer cap in the embodiment of the present invention. It is CC sectional view taken on the line in FIG. It is a principal part enlarged view of the nut member in embodiment of this invention. It is a schematic diagram which shows the nut member in one modification of this invention. It is sectional drawing of the linear part in one modification of this invention. It is sectional drawing of the linear part in one modification of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view of a ball screw device 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA in FIG. FIG. 3 is an enlarged view of a main part in FIG.
As shown in FIG.1 and FIG.2, the ball screw apparatus 1 has the screw shaft 2, the nut member 3, and the ball | bowl 4 (rolling body).

  As shown in FIG. 1, the screw shaft 2 has a spiral ball rolling groove 21 (rolling element rolling groove) on the outer peripheral surface 2a. As shown in FIG. 3, the ball rolling groove 21 is formed in a so-called gothic arc shape. That is, the ball rolling groove 21 is formed on the first groove surface 22 formed on one side in the axial direction (left side in FIG. 3) with respect to the groove center and on the other side in the axial direction (right side in FIG. 3). And a second groove surface 23.

  Each of the first groove surface 22 and the second groove surface 23 has an arc shape formed symmetrically with respect to the groove center. The arc-shaped centers of the first groove surface 22 and the second groove surface 23 do not coincide with each other, and the ball rolling groove 21 is formed such that the center portion of the groove is pointed. The ball 4 rolls on each of the first groove surface 22 and the second groove surface 23. That is, the ball 4 and the ball rolling groove 21 have a two-point contact structure.

  As shown in FIG. 1, the screw shaft 2 has a spiral escape groove 24 formed in the ball rolling groove 21. The escape groove 24 is formed in the center of the ball rolling groove 21 as shown in FIG. The escape groove 24 prevents the end portion of the tool to be finished from touching the other when finishing one of the first groove surface 22 and the second groove surface 23. The escape groove 24 is formed at the bottom of the ball rolling groove 21. The escape groove 24 has a concave shape and is formed deeper than the ball rolling groove 21.

  As shown in FIG. 2, the nut member 3 has a spiral ball load rolling groove 31 (rolling element load rolling groove) on the inner peripheral surface 3 b. The ball load rolling groove 31 faces the ball rolling groove 21. As shown in FIG. 3, the ball load rolling groove 31 is formed in a so-called gothic arc shape. That is, the ball load rolling groove 31 is formed on the first groove surface 34 formed on one side in the axial direction (left side in FIG. 3) with respect to the groove center and on the other side in the axial direction (right side in FIG. 3). Second groove surface 35.

  Each of the first groove surface 34 and the second groove surface 35 has an arc shape formed symmetrically with respect to the groove center. The arc-shaped centers of the first groove surface 34 and the second groove surface 35 do not coincide with each other, and the ball load rolling groove 31 is formed such that the center portion of the groove is pointed. The ball 4 rolls on each of the first groove surface 34 and the second groove surface 35. That is, the ball 4 and the ball load rolling groove 31 have a two-point contact structure. An escape groove 36 is also formed at the bottom of the ball load rolling groove 31.

  As shown in FIG. 2, the ball 4 is interposed between the ball rolling groove 21 and the ball load rolling groove 31. When the ball rolling groove 21 and the ball load rolling groove 31 face each other, the ball load rolling path 5 is formed in the facing portion. The ball 4 rolls in a state where a load is applied on the ball load rolling path 5. As shown in FIG. 1, the nut member 3 includes a return pipe 33 (rolling element circulation component). The return pipe 33 forms a ball circulation path 6 (rolling element circulation path) that connects one end and the other end of the ball load rolling path 5 (see FIG. 2).

  The ball circulation path 6 is formed in such a size that a load is hardly applied to the ball 4. When the ball load rolling path 5 and the ball circulation path 6 communicate with each other, an infinite circulation path for the balls 4 is formed. In other words, the ball 4 rolls in a spiral manner on the ball load rolling path 5, is then rolled up at the end of the return pipe 33 and is introduced into the ball circulation path 6. The ball 4 introduced into the ball circulation path 6 moves through the return pipe 33 and is introduced again at the head of the ball load rolling path 5.

FIG. 4 is an exploded perspective view of the nut member 3 in the embodiment of the present invention. FIG. 5 is a left side view of the nut member 3 with the cage cap 60 removed in the embodiment of the present invention. FIG. 6 is a right side view of the first retainer cap 61 in the present embodiment. 7 is a cross-sectional view taken along the line BB in FIG. FIG. 8 is a left side view of the second cage cap 62 in the present embodiment. 9 is a cross-sectional view taken along the line CC in FIG. FIG. 10 is an enlarged view of a main part of the nut member 3 in the embodiment of the present invention.
As shown in FIG. 4, the nut member 3 includes a nut main body 40, a ball cage 50 (rolling body cage), and a cage cap 60 (support member).

  The nut body 40 has a ball load rolling groove 31. The nut body 40 has a mounting groove 43 to which the cage cap 60 is attached. As shown in FIG. 2, the mounting groove 43 is formed on each of the end surfaces 41 and 42 in the axial direction of the nut body 40. The depth and shape of the mounting groove 43 are the same on each of the end faces 41 and 42. As shown in FIG. 5, the mounting groove 43 is formed in a circular shape in a side view and has a diameter larger than the diameter of the inner peripheral surface 3 b.

  As shown in FIG. 4, the ball cage 50 includes a spiral linear portion 51, a first extending portion 52 that extends from one end of the linear portion 51 to the radially outer side of the linear portion 51, and a wire A second extending portion 53 extending from the other end of the linear portion 51 to the radially outer side of the linear portion 51. The ball cage 50 has a spring property. As shown in FIG. 10, the linear portion 51 faces the ball load rolling groove 31 and holds the ball 4 in the ball load rolling groove 31. The linear portion 51 is disposed to face the center of the ball load rolling groove 31.

  The linear portion 51 has a rectangular cross section that extends in the axial direction of the screw shaft 2. As shown in FIG. 5, the linear portion 51 holds the ball 4 with an outward surface (circumferential surface) facing radially outward. As shown in FIG. 3, the linear portion 51 is accommodated in the escape groove 24 when the ball load rolling groove 31 faces the ball rolling groove 21. That is, the width of the linear portion 51 in the axial direction is smaller than the width of the relief groove 24 in the axial direction, and the thickness of the linear portion 51 in the radial direction is smaller than the depth of the relief groove 24 in the radial direction.

  The minimum distance of the gap between the linear portion 51 and the ball load rolling groove 31 is smaller than the diameter of the ball 4. Thereby, as shown in FIG. 10, it can prevent that the ball | bowl 4 falls from the ball | bowl load rolling groove 31. FIG. Further, the maximum distance between the linear portion 51 and the ball load rolling groove 31 is larger than the diameter of the ball 4. As a result, as shown in FIG. 3, it is possible to prevent the balls 4 coming into contact with the ball rolling groove 21 and the ball load rolling groove 31 from coming into contact with the linear portion 51.

  As shown in FIG. 4, the cage cap 60 is attached to the nut body 40 and holds the ball cage 50. The cage cap 60 includes a first cage cap 61 attached to the end surface 41 of the nut body 40 and a second cage cap 62 attached to the end surface 42 of the nut body 40. The first cage cap 61 holds the first extending portion 52 of the ball cage 50. The second cage cap 62 holds the second extending portion 53 of the ball cage 50.

  As shown in FIG. 5, the first extending portion 52 has a curved shape that curves more radially outward than the tangent line T of the linear portion 51. The first extending portion 52 extends radially outward from the inner peripheral surface 3 b of the nut body 40. The first extending portion 52 extends radially outward from the mounting groove 43 of the nut body 40 and faces the end surface 41 in the axial direction. The first extending portion 52 can be elastically deformed inward so as not to contact the inner peripheral surface 3b when the ball holder 50 is incorporated into the nut body 40. In addition, the 2nd extension part 53 is also set as the structure similar to the 1st extension part 52, and is formed symmetrically with the 1st extension part 52 on the basis of the axial center of the linear part 51 (refer FIG. 6). .

  As shown in FIGS. 6 and 7, the first retainer cap 61 includes a base portion 63, a fitting protrusion 64, and a first engagement groove 65. The first cage cap 61 is a resin molded part. The first retainer cap 61 has an opening 61a through which the screw shaft 2 passes in the center. The base portion 63 is formed in a disk shape having a cutout portion 63a that is partially cut out flat so that the direction of incorporation can be seen. As shown in FIG. 2, the fitting protrusion 64 is formed in a cylindrical shape that fits into the mounting groove 43. The fitting protrusion 64 protrudes in the axial direction with respect to the base part 63.

  As shown in FIG. 6, the first engagement groove 65 engages with the first extension portion 52. The first engagement groove 65 extends from the opening 61 a across the fitting protrusion 64 to the base 63. As shown in FIG. 7, the bottom surface 65 a of the first engagement groove 65 has an inclined shape that becomes deeper toward the base portion 63. In addition, as shown in FIG. 6, the first side wall surface 65 b of the first engagement groove 65 that contacts the outward surface 52 a of the first extension portion 52 is curved along the curve shape of the first extension portion 52. doing.

  As shown in FIGS. 8 and 9, the second cage cap 62 includes a base portion 66, a fitting protrusion 67, and a second engagement groove 68. The second cage cap 62 is a resin molded part. The second retainer cap 62 has an opening 62a through which the screw shaft 2 passes in the center. The base part 66 is formed in a disk shape having a notch part 66a that is partly cut out flat so that the mounting direction can be seen. As shown in FIG. 2, the fitting protrusion 67 is formed in a cylindrical shape that fits into the mounting groove 43. The fitting protrusion 67 protrudes in the axial direction with respect to the base portion 66.

  The second engaging groove 68 engages with the second extending portion 53 as shown in FIG. The second engagement groove 68 extends from the opening 62 a to the base portion 66 across the fitting protrusion 67. As shown in FIG. 9, the bottom surface 68 a of the second engagement groove 68 has an inclined shape that becomes deeper toward the base portion 66. Further, as shown in FIG. 8, the second side wall surface 68 b of the second engagement groove 68 that contacts the outward surface 53 a of the second extending portion 53 is curved along the curved shape of the second extending portion 53. doing.

The assembly of the nut member 3 having the above-described configuration is performed as follows.
First, as shown in FIG. 4, the ball cage 50 is inserted into the nut body 40. For example, when the ball holder 50 is inserted into the nut body 40 with the second extending portion 53 at the head, the second extending portion 53 is elastically deformed inward to avoid contact with the inner peripheral surface 3b. When the ball cage 50 is inserted into the nut body 40, the ball cage 50 is fixed with the cage cap 60.

  The cage cap 60 has a first cage cap 61 having a first engagement groove 65 that engages with the first extension portion 52, and a second engagement groove 68 that engages with the second extension portion 53. A second retainer cap 62. According to this configuration, the ball retainer 50 can be supported by the nut body 40 without changing the mold of the nut body 40 or performing additional groove processing on the nut body 40. The 1st retainer cap 61 engaged with the 1st extension part 52 is attached to the end surface 41 of the nut main body 40, as shown in FIG. The second cage cap 62 engaged with the second extending portion 53 is attached to the end surface 42 of the nut body 40.

  As shown in FIG. 5, the first extending portion 52 extends radially outward of the linear portion 51 and faces the end surface 41 of the nut body 40 in the axial direction. Although not shown, the second extending portion 53 similarly faces the end face 42 of the nut body 40 in the axial direction. Thereby, the ball holder 50 is prevented from coming off from the nut body 40. Moreover, the 1st extension part 52 contact | abuts in the axial direction with the bottom face 65a of the 1st engaging groove 65, as shown in FIG. Further, as shown in FIG. 8, the second extending portion 53 contacts the bottom surface 65 a of the second engaging groove 68 in the axial direction. Thereby, the ball cage 50 is positioned with respect to the nut body 40 in the axial direction.

  In addition, each of the first extending portion 52 and the second extending portion 53 has a curved shape that curves outward in the radial direction of the linear portion 51 from the tangent line T of the linear portion 51. As shown in FIG. 6, the first engagement groove 65 has a first side wall surface 65 b that curves along the curved shape of the first extension portion 52 and abuts on the outward surface 52 a of the first extension portion 52. As shown in FIG. 8, the second engagement groove 68 has a second side that curves along the curved shape of the second extending portion 53 and contacts the outward surface 53 a of the second extending portion 53. A wall surface 68b is provided. According to this configuration, the ball cage 50 is positioned with respect to the nut body 40 in the radial direction and the circumferential direction.

  If the first extending portion 52 and the second extending portion 53 are parallel, the ball cage 50 is easily moved in the radial direction by detaching from the first engaging groove 65 and the second engaging groove 68. End up. Therefore, in the present embodiment, each of the first extending portion 52 and the second extending portion 53 is curved, and the frictional force in the sliding direction between the first side wall surface 65b and the second side wall surface 68b is increased, and the ball cage 50 radial movements are prevented. Further, the ball cage 50 has a spring property, the outward surface 52a of the first extension portion 52 and the first side wall surface 65b abut on each other in the circumferential direction, and the outward surface 53b of the second extension portion 53. And the second side wall surface 68b abut on each other in the circumferential direction. Thereby, the ball cage 50 is positioned with respect to the nut body 40 in the radial direction and the circumferential direction.

  Next, the ball 4 is assembled into the nut body 40 to which the ball cage 50 is attached. As shown in FIG. 10, the linear portion 51 of the ball cage 50 holds the ball 4 in the ball load rolling groove 31 so as to face the ball load rolling groove 31. Thereby, the drop-off of the ball 4 from the nut body 40 is prevented. Therefore, the work of assembling the ball 4 can be easily performed without using a temporary shaft. After the ball 4 is assembled into the nut body 40, the return pipe 33 is inserted into the nut body 40 and fixed. Thus, the nut member 3 is assembled.

Subsequently, the assembly of the ball screw device 1 having the above-described configuration is performed as follows.
First, the nut member 3 assembled as described above is gripped, and the nut member 3 is screwed together while rotating from the end of the screw shaft 2. As shown in FIG. 2, the screw shaft 2 has a spiral escape groove 24 formed in the ball rolling groove 21, and the linear portion 51 of the ball cage 50 is accommodated in the escape groove 24. Further, by using the escape groove 24 of the ball rolling groove 21 as the accommodating portion of the spiral linear portion 51, the accommodating portion of the linear portion 51 can be formed without increasing the number of processing steps.

  When the nut member 3 is screwed onto the screw shaft 2, the ball 4 comes into contact with the ball rolling groove 21 and leaves the linear portion 51 as shown in FIG. 3. Therefore, the ball cage 50 does not interfere with the screw shaft 2 or the ball 4. The ball 4 is interposed between the ball rolling groove 21 and the ball load rolling groove 31. Thereby, the screw shaft 2 and the nut member 3 can be relatively rotated via the ball 4. Thus, the ball screw device 1 is assembled.

  Thus, according to the above-described embodiment, the screw shaft 2 having the spiral ball rolling groove 21 on the outer peripheral surface 2a and the spiral ball load facing the ball rolling groove 21 on the inner peripheral surface 3b. A ball screw device having a nut member 3 having a rolling groove 31 and a plurality of balls 4 interposed between the ball rolling groove 21 and the ball load rolling groove 31. Opposed to the load rolling groove 31, the ball load rolling groove 31 has a ball holder 50 having a spiral linear portion 51 that holds the ball 4, and the screw shaft 2 is formed in the ball rolling groove 21. By adopting a configuration in which the spiral-shaped escape groove 24 is provided and the linear portion 51 of the ball cage 50 is accommodated in the escape groove 24, the ball 4 can be dropped without using a temporary shaft. The ball screw device 1 and the nut member 3 that can be prevented are obtained. .

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, the following modifications can be adopted. In the following description, the same or equivalent components as those in the above-described embodiment are denoted by the same or equivalent symbols, and the description thereof is simplified or omitted.

FIG. 11 is a schematic diagram showing a nut member 3A according to a modification of the present invention.
A nut member 3 </ b> A shown in FIG. 11 has a fluid supply device 70. A ball cage 50A shown in FIG. 11 is formed in a pipe shape through which a fluid can flow, and a plurality of openings are formed in the linear portion 51 so that the fluid can be ejected. The fluid supply device 70 supplies fluid such as lubricating oil and cooling gas to the ball cage 50A. According to this configuration, the ball holder 50 can have a predetermined function even when the nut member 3 </ b> A is screwed onto the screw shaft 2.

FIG. 12 is a cross-sectional view of the linear portions 51A to 51D in one modification of the present invention.
A linear portion 51A shown in FIG. 12A has a circular cross section. A linear portion 51B shown in FIG. 12B has a triangular cross section. A linear portion 51C shown in FIG. 12C has a trapezoidal cross section. A linear portion 51D shown in FIG. 12D has a semicircular cross section.
According to the linear portion 51A shown in FIG. 12A, since the cross section is circular, the linear material itself may be formed in a spiral shape, and the ball holder 50 can be formed easily and at low cost. In addition, according to the linear portions 51B to 51D shown in FIGS. 12B to 12D, although a predetermined process is required, the ball 4 can be held in a flat surface, so that the stability of holding the ball is increased. The linear portions 51 </ b> A to 51 </ b> D are preferably selected as appropriate according to the shape of the escape groove 24.

FIG. 13 is a cross-sectional view of the linear portions 51E to 51H according to a modification of the present invention.
A linear portion 51E shown in FIG. 13A is in contact with the ball 4 on a curved surface, and a groove 81 for holding lubricating oil is formed at the center of the curved surface. A linear portion 51F shown in FIG. 13B has a U-shaped cross section. A linear portion 51G shown in FIG. 13C has an H-shaped cross section. A linear portion 51D shown in FIG. 13 (d) has a T-shaped cross section.
According to the linear portion 51E shown in FIG. 13A, the ball 4 is in contact with the curved surface, so that the stability of holding the ball is further increased. Further, by holding the lubricating oil in the groove 81, the lubricating oil can be supplied to the balls 4 even while the nut member 3 is being conveyed alone. According to the linear portions 51F to 51H shown in FIGS. 13B to 13D, the moment of inertia of the cross section can be increased, and even when the nut member 3 is long in the axial direction, the ball cage 50 is prevented from being bent. it can.

  Further, for example, in the above embodiment, the ball screw device 1 and the nut member 3 having the return pipe 33 are illustrated, but the present invention is not limited to this configuration, and is described in, for example, Japanese Patent No. 4897543. As shown, the ball may circulate through the end piece.

  Further, for example, in the above-described embodiment, the dedicated cage cap 60 that holds the ball cage 50 is illustrated, but the present invention is not limited to this configuration. For example, Japanese Patent Laid-Open No. 5-44810 discloses As described, it may be configured to also serve as a ball screw dustproof seal.

  Further, for example, in the above embodiment, the configuration in which the ball load rolling groove 31 has a Gothic arc shape is illustrated, but the present invention is not limited to this configuration. For example, the ball load rolling groove 31 has a circular shape. The configuration may be an arc shape.

  Moreover, the said embodiment and modification can be combined suitably in the range which is not mutually contradictory.

  DESCRIPTION OF SYMBOLS 1 ... Ball screw apparatus, 2 ... Screw shaft, 2a ... Outer peripheral surface, 3 (3A) ... Nut member, 3b ... Inner peripheral surface, 4 ... Ball (rolling element), 21 ... Ball rolling groove (Rolling element rolling groove) ), 24 ... Escape groove, 30b ... Inner circumferential surface, 31 ... Ball load rolling groove (rolling element load rolling groove), 40 ... Nut body, 41 ... End face, 42 ... End face, 50 (50A) ... Ball cage , 51 (51A to 51H) ... linear part, 52 ... first extension part, 52a ... outward face, 53 ... second extension part, 53a ... outward face, 60 ... cage cap (support member), 61 ... 1st cage cap (first support member), 62 ... 2nd cage cap (2nd support member), 65 ... 1st engagement groove, 65b ... 1st side wall surface, 68 ... 2nd engagement groove , 68b ... second side wall surface

Claims (5)

A screw shaft having a spiral rolling element rolling groove on the outer peripheral surface, a nut member having a spiral rolling element load rolling groove facing the rolling element rolling groove on the inner peripheral surface, and the rolling element rolling A ball screw device having a plurality of rolling elements interposed between a groove and the rolling element load rolling groove,
The nut member has a rolling element holder that has a spiral linear portion that faces the rolling element load rolling groove and holds the rolling element in the rolling element load rolling groove,
The screw shaft has a spiral escape groove formed in the rolling element rolling groove,
The ball screw device, wherein the linear part of the rolling element cage is accommodated in the escape groove. The nut member is
A nut body having the rolling element load rolling groove;
The ball screw device according to claim 1, further comprising a support member attached to the nut body and supporting the rolling element holder. The rolling element cage is:
A first extending portion extending from one end of the linear portion to the radially outer side of the linear portion and facing one end surface of the nut body in the axial direction;
A second extending part extending from the other end of the linear part to the outside in the radial direction of the linear part and facing the other end face of the nut body in the axial direction;
The support member is
A first support member having a first engagement groove for engaging with the first extension portion;
The ball screw device according to claim 2, further comprising: a second support member having a second engagement groove that engages with the second extending portion. Each of the first extending portion and the second extending portion has a curved shape that curves outward in the radial direction of the linear portion with respect to the tangent line of the linear portion,
The first engagement groove has a first side wall surface that is curved along the curved shape of the first extension portion and contacts the outward surface of the first extension portion,
The said 2nd engagement groove | channel has a 2nd side wall surface which curves along the curve shape of the said 2nd extension part, and contact | abuts to the outward surface of the said 2nd extension part. 4. The ball screw device according to 3. A nut member having a spiral rolling element load rolling groove on the inner peripheral surface,
A plurality of rolling elements,
A nut member comprising: a rolling element holder having a spiral linear portion that holds the rolling element in the rolling element load rolling groove facing the rolling element load rolling groove.

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